Dual damascene interconnection with metal-insulator-metal capacitor and method of fabricating

ABSTRACT

Provided are a dual damascene interconnection with a metal-insulator-metal (MIM) capacitor and a method of fabricating the same. In this structure, an MIM capacitor is formed on a via-level IMD. After the via-level IMD is formed, while an alignment key used for patterning the MIM capacitor is being formed, a via hole is formed to connect a lower electrode of the MIM capacitor and an interconnection disposed under the via-level IMD. Also, an upper electrode of the MIM capacitor is directly connected to an upper metal interconnection during a dual damascene process.

CROSS REFERENCES TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.10/799,292, filed on Mar. 12, 2004, which claims the priority of KoreanPatent Application No. 2003-21036, filed on Apr. 3, 2003, in the KoreanIntellectual Property Office, the contents of which are incorporatedherein by reference in their entirety by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor device and a method offabricating the same. More particularly, the present invention relatesto a dual damascene interconnection with a metal-insulator-metal (MIM)capacitor and a method of fabricating the same.

2. Description of the Related Art

To improve the speed of semiconductor devices, there have been intensivestudies on methods of reducing RC delays using low-resistanceinterconnections and low-k intermetal dielectrics (IMDs). Copperinterconnections have a lower resistance than conventional aluminuminterconnections and a relatively high resistance to electromigration,thus improving the reliability of semiconductor devices. Also, copperrequires low power consumption and low price and thus has been widelyused as interconnection material.

However, since copper is not easily etched, patterning a copper layer ina desired shape is very difficult. Thus, a damascene process is used.That is, after a groove is formed in an interconnection shape bypatterning an IMD, copper is filled in the groove and then planarizedusing chemical mechanical polishing (CMP) to be on the same level withthe IMD. In particular, a dual damascene process is widely used in whicha via hole is formed and a line trench is formed over the via hole tooverlap the via hole, and the via hole and the line trench aresimultaneously filled with copper using a one-time deposition. Bycomparison, a via may be formed using a damascene process and then aline trench may be formed using another damascene process. In this case,the via and the line are each formed using a single damascene process.

Also, extensive studies have been made on metal-insulator-metal (MIM)capacitors, in which electrodes have no depletion and low-resistancemetals are used, unlike conventional capacitors having an upperelectrode and a lower electrode that are formed of polysilicon. However,when an MIM capacitor is formed in a conventional dual damasceneinterconnection, a dual damascene process has to be altered and thefabrication process becomes complex.

FIGS. 1 and 2 show conventional structures in which electrodes of an MIMcapacitor are connected to interconnections using vias. To form theseconventional structures, an MIM capacitor is formed before a via-levelIMD is formed and an electrode of the MIM capacitor is connected to aninterconnection by a via. However, in this case, as shown in FIGS. 1 and2, a via that will be formed on the MIM capacitor and a via that willconnect upper and lower interconnections are formed to different depths.As a result, a dual damascene process needs an etch process having avery high etch selectivity.

To form the structure shown in FIG. 1, a lower metal interconnection 4and a lower electrode 6 of an MIM capacitor are formed using a copperdamascene process on the same level in an insulating layer 2. Acapacitor dielectric layer 8 is coated on the resultant structure, andthen an upper electrode 10 and a capping layer 12 are sequentiallyformed. Next, an IMD 14 is formed, and then a via 16 a connected to thelower metal interconnection 4, a via 18 a connected to the lowerelectrode 6, and a via 20 a connected to the upper electrode 10 areformed using a dual damascene process. Thereafter, upper metalinterconnections 16 b, 18 b, and 20 b are formed on the vias 16 a, 18 a,and 20 a, respectively.

In the structure shown in FIG. 1, the types of available dielectriclayers 8 are limited. The dielectric layer 8 should function as both acapacitor dielectric layer and a diffusion barrier layer to copper thatis used to form the lower electrode 6. Thus, the dielectric layer 8 isactually a silicon nitride layer. Also, since the lower electrode 6 ispolished using chemical mechanical polishing (CMP) during the dualdamascene process, its surface morphology is degraded. Thus, thecharacteristics of the MIM capacitor depend on the integrity of aninterface between the lower electrode 6 and the dielectric layer 8.Also, the copper constituting the lower electrode 6 diffuses into thedielectric layer 8. Most seriously, the vias 16 a and 18 a connectingthe upper and lower interconnections are formed to a different depthfrom that of the via 20 a formed on the MIM capacitor. Thus, an etchprocess having a very high etch selectivity is needed during the dualdamascene process. To form the vias 16 a and 18 a separately from thevia 20 a because of the etch selectivity, an additional mask isrequired. Thus, the dual damascene process must be modified.

In FIG. 2, only a lower metal interconnection 24 is formed in theinsulating layer 22 using a copper damascene process. A diffusionbarrier layer 25 is formed on the insulating layer 22, and a lowerelectrode 26 of an MIM capacitor is formed using, for example, TaN.Then, a capacitor dielectric layer 28 and an upper electrode 30 aresequentially formed on the resultant structure. A capping layer 32 andan IMD 34 are formed on the upper electrode 30. Thereafter, a via 36 aconnected to the lower metal interconnection 24, a via 38 a connected tothe lower electrode 26, and a via 40 a connected to the upper electrode30 are formed using a dual damascene process, and upper metalinterconnections 36 b, 38 b, and 40 b are formed on the vias 36 a, 38 a,and 40 a, respectively.

In the structure shown in FIG. 2, since the lower electrode 26 is notformed of copper, the types of material used in the dielectric layer 28are more numerous compared to the structure of FIG. 1. Thus, thedielectric layer 28 can be formed of even high-k dielectric material.Nevertheless, in this structure, three different-type vias 36 a, 38 a,and 40 a are formed requiring an etch process having a high etchselectivity or an additional photolithographic process. Therefore, thedual damascene process must be modified.

FIG. 3 shows another conventional structure in which an MIM capacitor isconnected to an AlCu interconnection. In this structure, lowerinterconnections 42 a and 42 b are formed of AlCu, and then aninsulating layer 44 is formed. Next, vias 46 a, 46 b, and 46 c areformed of W using a single damascene process, and a lower electrode 48,a dielectric layer 50, and an upper electrode 52 are formed on the vias46 a and 46 b to complete an MIM capacitor. Thus, the lower electrode 48is connected to the lower interconnection 42 a by the vias 46 a and 46b. Next, a first IMD 54 is formed, an AlCu interconnection 55 is formedusing a single damascene process, and a second IMD 56 is depositedthereon. Similarly, through a single damascene process, a W stud 58 aconnected to the upper electrode 52 and a W stud 58 b connected to theAlCu interconnection 55 are formed in the second IMD 56.

In this case, unlike the cases described with reference to FIGS. 1 and2, problems of an etch process due to different types of vias can besolved. However, since the single damascene process is performed severaltimes, the copper dual damascene process must be somewhat modified.Also, while the MIM capacitor is being fabricated, the via 46 c isexposed to an etching atmosphere, thus degrading the yield andreliability of the via 46 c. To solve these problems, the vias 46 a and46 b formed under the MIM capacitor and the via 46 c connecting theupper and lower interconnections 42 b and 55 should be formed usingseparate processes. However, this case necessitates an additionalphotolithography process.

SUMMARY OF THE INVENTION

The present invention provides a method of fabricating a dual damasceneinterconnection with an MIM capacitor by forming the MIM capacitorwithout modifying a dual damascene process and using additional masks.

The present invention also provides a dual damascene interconnectionwith a reliable MIM capacitor.

In accordance with an aspect of the present invention, there is provideda method of fabricating a dual damascene interconnection with an MIMcapacitor, the method comprising forming a via-level IMD on a substratewhere first and second lower metal interconnections are formed, andforming a via hole for connecting a lower electrode of an MIM capacitorand the first lower metal interconnection by patterning the via-levelIMD. Next, a metal layer for a capacitor lower electrode, a capacitordielectric layer, and a metal layer for a capacitor upper electrode aresequentially formed on the surface of the substrate. Then, the metallayer for the lower electrode, the capacitor dielectric layer, and themetal layer for the upper electrode, which are disposed over the viahole, are patterned to form the MIM capacitor, which includes a lowerelectrode, a dielectric layer, and an upper electrode. A trench-levelIMD is formed on the via-level IMD including the MIM capacitor, and thenthe via-level IMD and the trench-level IMD are etched, therebysimultaneously forming a groove for a dual damascene interconnection,exposing the second lower metal interconnection, and a trench exposingthe upper electrode. The groove for the dual damascene interconnectionand the trench are filled with a metal, thereby forming a dual damasceneinterconnection connected to the second lower metal interconnection andan upper metal interconnection connected to the upper electrode.

In one embodiment, formation of the first lower metal interconnectionand the second metal interconnection comprises: forming an insulatinglayer on the substrate; and forming the first lower metalinterconnection and the second lower metal interconnection by fillingthe insulating layer with a metal using a damascene process.

The via hole can be formed in a hole shape. The via hole can be formedin a line shape.

In one embodiment, the method further comprises: forming an etch stoplayer between the first and second lower metal interconnections and thevia-level intermetal dielectric; and forming another etch stop layerbetween the via-level intermetal dielectric and the trench-levelintermetal dielectric.

In one embodiment, the method further comprises forming themetal-insulator-metal capacitor using one masking process and thenreducing the area of the upper electrode by etching edges of the upperelectrode.

The lower electrode can directly contact the first lower metalinterconnection by the via hole.

In one embodiment, the method further comprises, after forming the viahole, further comprising forming a via for connecting the lowerelectrode and the first lower metal interconnection by filling the viahole with a conductive material and then planarizing the filledconductive material.

The formation of the groove for the dual damascene interconnection caninclude forming the via hole and the line trench using a via-first dualdamascene process. While the line trench is being formed, the trenchexposing the upper electrode is formed.

In one embodiment, formation of the groove for the dual damasceneinterconnection includes forming a via hole and a line trench using aline trench-first dual damascene process.

In one embodiment, the dual damascene interconnection is formed of atleast one of copper, gold, silver, tungsten, and any alloy thereof.

In one embodiment, while the via hole for connecting the lower electrodeof the metal-insulator-metal capacitor and the first lower metalinterconnection is being formed, an alignment key for aligning themetal-insulator-metal capacitor is formed by patterning the via-levelintermetal dielectric. The formation of the metal-insulator-metalcapacitor includes leaving the metal layer for the lower electrode, thecapacitor dielectric layer, and the metal layer for the upper electrodeon the inner walls of the alignment key by performing an anisotropicetchback process. While the dual damascene interconnection and the uppermetal interconnection are being formed, a dummy interconnection can beformed by filling a stepped region of the alignment key.

In accordance with another aspect of the present invention, there isprovided a dual damascene interconnection with an MIM capacitorcomprising a via-level IMD and a trench-level IMD which are sequentiallystacked on a substrate; a dual damascene interconnection formed in thevia-level IMD and the trench-level IMD; and an MIM capacitor formedbetween the via-level IMD and the trench-level IMD to include a lowerelectrode, a dielectric layer, and an upper electrode.

In one embodiment, the first lower metal interconnection and the secondlower metal interconnection are damascene interconnections buried in aninsulating layer formed on the substrate. The via can be filled in ahole-type opening. The via is filled in a line-type opening.

In one embodiment, the lower electrode, the dielectric layer, and theupper electrode are patterned to have the same area.

The upper electrode can be patterned to have a smaller area than that ofeach of the lower electrode and the capacitor dielectric layer.

The via can be integrally formed with the lower electrode.

In one embodiment, an alignment key is formed in the via-levelintermetal dielectric so as to have the step difference to align themetal-insulator-metal capacitor. In one embodiment, the metal layer forthe lower electrode, the dielectric layer, and the metal layer for theupper electrode are on the inner walls of the alignment key. Thestructure further includes a dummy interconnection in a stepped regionof the alignment key.

In one embodiment, the dual damascene interconnection is formed of atleast one material selected from the group consisting of copper, gold,silver, tungsten, and any alloy thereof.

The via and the dual damascene interconnection can be formed ofdifferent materials.

In one embodiment, the structure further comprises: a first lower metalinterconnection and a second lower metal interconnection formed betweenthe substrate and the via-level intermetal dielectric; and an uppermetal interconnection formed on and connected to the upper electrode.The lower electrode is directly connected to the first lower metalinterconnection, and the dual damascene interconnection is connected tothe second metal interconnection.

According to the present invention, an MIM capacitor can be fabricatedwithout modifying a dual damascene process and the yield and reliabilityof the MIM capacitor can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages of theinvention will be apparent from the more particular description of apreferred embodiment of the invention, as illustrated in theaccompanying drawings in which like reference characters refer to thesame parts throughout the different views. The drawings are notnecessarily to scale, emphasis instead being placed upon illustratingthe principles of the invention.

FIGS. 1 and 2 show conventional structures in which electrodes of an MIMcapacitor are connected to interconnections using vias.

FIG. 3 shows another conventional structure in which an MIM capacitorand an AlCu interconnection are formed.

FIGS. 4 through 10 are cross-sectional views illustrating a method offabricating a dual damascene interconnection with an MIM capacitoraccording to an embodiment of the present invention.

FIGS. 11 through 13 are cross-sectional views illustrating a method offabricating a dual damascene interconnection with an MIM capacitoraccording to another embodiment of the present invention.

FIGS. 14 through 16 are cross-sectional views of a dual damasceneinterconnection with an MIM capacitor according to yet anotherembodiment of the present invention.

FIG. 17 is a cross-sectional view of a dual damascene interconnectionwith an MIM capacitor according to another embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE INVENTION Embodiment 1

FIGS. 4 through 10 are cross-sectional views illustrating a method offabricating a dual damascene interconnection with an MIM capacitoraccording to an embodiment of the present invention. While only copperis used as interconnection material in embodiments of the presentinvention for clarity of description, other metals, such as aluminum,gold, silver, and tungsten, can be used instead of copper.

Referring to FIG. 4, an insulating layer 100 is formed on a substrate(not shown) and then filled with a metal using a damascene process,thereby forming a first lower metal interconnection 105 a and a secondlower metal interconnection 105 b. If the first and second lower metalinterconnections 105 a and 105 b are copper interconnections, adiffusion barrier layer is preferably further formed using sputtering atan interface between the insulating layer 100 and each of the first andsecond lower metal interconnections 105 a and 105 b. The diffusionbarrier layer, which prevents diffusion and oxidation of copper, may beformed of at least one of Ta, TaN, TaSiN, TiN, TiSiN, WN, and WSiN.

Next, an etch stop layer 110, which also functions as a diffusionbarrier layer, is formed by depositing silicon nitride usingplasma-enhanced chemical vapor deposition (PECVD), and then a via-levelIMD 115 is deposited. The via-level IMD 115 is formed of a low-kdielectric material so as to reduce RC delay. For example, the via-levelIMD 115 is formed of black diamond, fluorine silicate glass (FSG), SiOC,polyimide, or SiLK™. Here, the etch stop layer 110 is formed to athickness of about 500 Å to 1000 Å, for example, 700 Å. Although thevia-level IMD 115 is formed to a thickness of about 4000 Å to 8000 Å,preferably 6000 Å, it is possible to adjust the thickness of thevia-level IMD 115 depending on whether the via-level IMD 115 is used ata lower end of the resultant structure close to a gate or at an upperend thereof far from the gate.

A photoresist layer 120 is patterned so as to define an opening A, whichexposes a region where an alignment key for adjusting the alignmentduring patterning of a capacitor will be formed, and an opening B, whichexposes a region where a via for connecting a lower electrode of the MIMcapacitor and the first lower metal interconnection 105 a will beformed. Here, while the via-region opening B may be formed as any one ofa hole-type and a line-type, it is preferably formed as a line-typegiven a subsequent process of filling a metal in it. As is known tothose skilled in the art, the alignment key refers to an element formedin the via-level IMD 115 so as to have the step difference to facilitatethe alignment of patterns during a subsequent photolithography process.

Referring to FIG. 5, the via-level IMD 115 is patterned by an etchprocess using the photoresist layer 120 as an etch mask, and the etchstop layer 110 disposed under each opening also is removed to expose acontact region. As described above, while the alignment key 130 foraligning the capacitor is being formed, a via hole 135 for connectingthe first lower metal interconnection 105 a to the lower electrode isformed together. Thereafter, the photoresist layer 120 is removed.

Referring to FIG. 6, a metal layer 140 for a capacitor lower electrode,a capacitor dielectric layer 145, and a metal layer 150 for a capacitorupper electrode are sequentially formed on the entire surface of thevia-level IMD 115. Here, the metal layer 140 for the lower electrode isformed so as to fill the via hole 135 such that the lower electrodedirectly contacts the first lower metal interconnection 105 a by the viahole 135. To fill a narrow space in the via hole 135, the metal layer140 for the lower electrode is formed using CVD. The metal layer 140 forthe lower electrode and the metal layer 150 for the upper electrode areformed of, for example, Ta, TaSiN, TiN, TiSiN, WN, or WSiN. Thecapacitor dielectric layer 145 may be formed of one of silicon nitride,silicon carbide, a combination of silicon nitride and oxide, and acombination of silicon carbide and oxide. Also, the dielectric layer 145may be formed of hafnium oxide or aluminium oxide, which has a higherdielectric constant than the foregoing dielectric materials.

Referring to FIG. 7, to form an MIM capacitor, a photoresist pattern 155is formed on the metal layer 150 for the upper electrode and the entiresurface of the resultant structure is etched back using the photoresistpattern 155 as an etch mask. When the photoresist pattern 155 is formed,the step difference of the alignment key 130 is utilized. Since themetal layer 140 for the lower electrode, the capacitor dielectric layer145, and the metal layer 150 for the upper electrode are etched andremoved, an MIM capacitor 160, which includes a lower electrode 140 a, adielectric layer 145 a, and an upper electrode 150 a, is formed onlyunder the photoresist pattern 155. A metal layer 140 b for the lowerelectrode, a capacitor dielectric layer 145 b, and a metal layer 150 bfor the upper electrode may remain also on the inner walls of thealignment key 130 (i.e., a stepped region) because of an anisotropicetching characteristic of the etchback process. However, since theremaining layers 140 b, 145 b, and 150 b are not connected to anyinterconnections, they may not be removed as shown in FIG. 7. Here, viasdo not exist in regions other than under the MIM capacitor 160. Thus,when the MIM capacitor 160 is patterned, vias are not damaged.

Referring to FIG. 8, after the photoresist pattern 155 is removed, toremove metallic residue that may remain on the sidewalls of the MIMcapacitor 160 when the MIM capacitor 160 is patterned, etching edges ofthe upper electrode 150 a to shrink the area of the upper electrode 150a is further performed. As a result, the MIM capacitor 160′ includes anupper electrode 150 a′, the area of which is smaller than that of thelower electrode 140 a or the dielectric layer 145 a. Thereafter, siliconnitride or silicon carbide is deposited on the MIM capacitor 160′,thereby forming an etch stop layer 165 required for a dual damasceneprocess. However, the etch stop layer 165 may not be formed. Next, atrench-level IMD 170 is formed on the etch stop layer 165. Like thevia-level IMD 150, the trench-level IMD 170 is formed of black diamond,fluorine silicate glass (FSG), SiOC, polyimide, or SiLK™, which is alow-k dielectric material for reducing RC delay. Although thetrench-level IMD 170 may be formed to a thickness of about 4000 Å to7000 Å, preferably, 5500 Å, it is possible to adjust the thicknessaccording to the positions where the trench-level IMD 170 is formed.

Referring to FIG. 9, the via-level IMD 115 and the trench-level IMD 170are etched using a typical copper dual damascene process, therebyforming a via hole 175 for a dual damascene interconnection and a linetrench 180, which expose the second metal interconnection 105 b. Here,the formation of the via hole 175 for the dual damascene interconnectionmay be followed by the formation of the line trench 180. While the linetrench 180 is being formed, a trench 182 also is formed to expose theupper electrode 150 a′ of the MIM capacitor 160′. However, it is alsopossible that the formation of the line trench 180 be followed by theformation of the via hole 175 for the dual damascene interconnection.

FIG. 10 shows a structure obtained by filling the stepped region of thealignment key 130, the trench 182, and the via hole 175 and the linetrench 180 with copper and then carrying out a CVD process to theresultant structure shown in FIG. 9. In FIG. 10, reference numeral 190denotes a copper dual damascene interconnection, 192 denotes an uppermetal interconnection, and 194 denotes a dummy interconnection formed ofcopper filled in the stepped region of the alignment key 130.

The detailed process will be described hereinafter. A cleaning processis performed to the resultant structure where the via hole 175 for thedual damascene interconnection, the line trench 180, and the trench 182are formed, and then a barrier metal layer (not shown) is formedthereon. The barrier metal layer is used to prevent diffusion of copper,which will be filled in the via hole 175 for the dual damasceneinterconnection, the line trench 180, and the trench 182, into adjacentregions. The barrier metal layer (not shown) can be formed to athickness of about 200 Å to 1000 Å, preferably, 450 Å, and using one ofTi, Ta, W, TiN, TaN, and WN. Also, the barrier metal layer (not shown)can be deposited using CVD or sputtering. Next, the via hole 175 for thedual damascene interconnection, the line trench 180, and the trench 182are filled with copper. Here, sputtering or CVD is typically used but itis also possible to use plating including electroplating and electrolessplating. When the copper is filled using plating, a seed metal layer(not shown) is preferably formed first on the barrier metal layer. Theseed metal layer improves the uniformity of the plated layer andfunctions as a region where the initial nuclei are grown. The seed metallayer may be formed to a thickness of about 500 Å to 2500 Å, preferably1500 Å. While the seed metal layer may be typically formed usingsputtering, it is possible to use a CVD method instead. The sputteringis performed in conditions where, for example, a temperature of thesubstrate is 0° C., a sputter power is 2 kW, a pressure is 2 mTorr, anda distance between a target seed metal layer and the substrate is 60 mm.The seed metal layer is formed of Cu, Au, Ag, Pt, or Pd. A seed metal isselected according to the types of plated layer and the plating method.Since a plated copper layer contains minute grains and has a somewhatsparse structure, an annealing process is preferably performed to growthe grains through re-crystallization and thus reduce resistivity. Next,the top surface of the resultant structure is planarized using chemicalmechanical polishing (CMP) until the top surface of the trench-level IMD170 is exposed. Thus, a dual damascene interconnection 190, an uppermetal interconnection 192, and a dummy interconnection 194 are formed.

As described above, after the via-level IMD 115 is formed, while thealignment key 130 is being formed to align the MIM capacitor 160′, thelower electrode 140 a of the MIM capacitor 160′ is connected to thefirst lower metal interconnection 105 a disposed under the via-level IMD115. Also, the upper electrode 150 a′ of the MIM capacitor 160′ isdirectly connected to the upper metal interconnection 192 during thecopper dual damascene process. This enables the fabrication of a copperinterconnection having the reliable MIM capacitor 160′ without anyadditional photolithography process. Further, damage to vias can beprevented during patterning of the MIM capacitor 160′, and the copperdual damascene process needs no modifications.

As shown in FIG. 10, the dual damascene interconnection with the MIMcapacitor 160′ according to the present invention comprises thevia-level IMD 115 and the trench-level IMD 170, which are sequentiallystacked on the substrate, the dual damascene interconnection 190 formedin the IMDs 115 and 170, and the MIM capacitor 160′, which is formedbetween the via-level IMD 115 and the trench-level IMD 170 and includesthe lower electrode 140 a, the dielectric layer 145 a, and the upperelectrode 150 a′.

The structure shown in FIG. 10 has the following characteristics. First,the MIM capacitor 160′ is formed on the structure where the via-levelIMD 115 is formed. In particular, the lower electrode 140 a directlycontacts the first lower metal interconnection 105 a. That is, the lowerelectrode 140 a and a via are integrally formed. Second, the alignmentkey 130 for aligning the MIM capacitor 160 is further included insidethe via-level IMD 115, and the metal layer 140 b for the lowerelectrode, the dielectric layer 145 b, and the metal layer 150 b for theupper electrode may be further included in the inner walls of thealignment key 130, and the dummy interconnection 194 may be furtherincluded on the alignment key 130. Third, the upper electrode 150 a′ canbe directly connected to the upper metal interconnection 192 withoutvias.

In this structure, an ideal MIM capacitor can be formed withoutmodifying a dual damascene process. Also, like the trench used forforming the upper metal interconnection connected to the upperelectrode, the line trench used for forming the copper dual damasceneinterconnection also is formed by etching the trench-level IMD 170 andthe etch stop layer 165. Further, since vias are not damaged during theformation of the MIM capacitor, the copper dual damascene process can bestably carried out.

Embodiment 2

FIGS. 11 through 13 are cross-sectional views illustrating a method offabricating a dual damascene interconnection with an MIM capacitoraccording to another embodiment of the present invention. The presentembodiment is a modified version of the first embodiment.

To begin, the process steps as described with reference to FIGS. 4 and 5are performed. Next, as shown in FIG. 11, a metal layer 137 is depositedon the entire surface of a via-level IMD 115 using CVD so as tocompletely fill a via hole 135.

Then, as shown in FIG. 12, an etchback process or a CMP process iscarried out, thereby completing a via 137 a connected to a first lowermetal interconnection 105 a. A metal layer 137 b may remain on the innerwalls of an alignment key 130 as shown in FIG. 12. However, since theremaining metal layer 137 b is not connected to any interconnection, itmay or may not be removed. Next, a metal layer for a lower electrode, acapacitor dielectric layer, and a metal layer for an upper electrode aresequentially stacked and patterned, thereby forming an MIM capacitor160′, which includes a lower electrode 140 a connected to the via 137 a,a dielectric layer 145 a, and an upper electrode 150 a′. As describedabove, in the present embodiment, the MIM capacitor 160′ is formed onthe via 137 a formed by an additional process. Subsequent processes areperformed as described with reference to FIGS. 8 through 10. As aresult, the resultant structure shown in FIG. 13 is obtained.

Embodiment 3

FIGS. 14 through 16 are cross-sectional views of a dual damasceneinterconnection with an MIM capacitor according to yet anotherembodiment of the present invention. In the present embodiment, variousmodified examples of electrodes of the MIM capacitor will be described.Structures shown in FIGS. 14 through 16 are obtained based on the secondembodiment. However, they may be identically obtained based on the firstembodiment or any other methods.

Referring to FIG. 14, a patterning process is performed using a metallayer 140 for a lower electrode, a capacitor dielectric layer 145, and ametal layer 150 for an upper electrode as a mask, thereby forming an MIMcapacitor 160, which includes a lower electrode 140 a, a dielectriclayer 145 a, and an upper electrode 150 a, which have the same area. Thestructure shown in FIG. 14 is obtained without etching edges of theupper electrode 150 a. Thus, unlike other structures, one mask can besaved.

By comparison, referring to FIG. 15, a metal layer for a lower electrodeis first formed and patterned to form a lower electrode 140 a, and adielectric layer 145 and a metal layer 150 for an upper electrode arestacked on the lower electrode 140 a and then patterned. Thus, an MIMcapacitor 160″, which includes the lower electrode 140 a, a dielectriclayer 145 a′, and an upper electrode 150 a″, is formed.

Also, referring to FIG. 16, an etch stop layer is not formed on an MIMcapacitor 160 on the entire surface of a via-level IMD 115. That is, adiffusion barrier layer 167 is formed to cover only the MIM capacitor160. Like the example shown in FIG. 14, since etching edges of an upperelectrode 150 a is not required, one mask can be saved.

Embodiment 4

FIG. 17 is a cross-sectional view of a dual damascene interconnectionwith an MIM capacitor according to another embodiment of the presentinvention.

Referring to FIG. 17, a device isolation layer (e.g., an STI) 202 isformed on a substrate 200, and a gate electrode 204 is formed thereon.Interlayer dielectrics (ILDs) L0, L1, . . . , and L7 and IMDs L8 and L9,which include a variety of interconnections, are formed on the basicstructure. The ILD L0 is formed to a thickness of about 2000 Å to 5000Å, and each of the ILDs L1, L2, . . . , and L7 is formed to a thicknessof about 6000 Å to 10000 Å. Also, each of the IMDs L8 and L9 is formedto a thickness of about 8000 Å to 15000 Å.

A first lower metal interconnection 205 a formed in the ILD L7 isconnected to a lower electrode 240 a, which is integrally formed with avia on the IMD L8. The lower electrode 240 a, a dielectric layer 245,and an upper electrode 250 a′ constitute an MIM capacitor 260′. Also, asecond lower metal interconnection 205 b formed in the ILD L7 isconnected to a dual damascene interconnection 290 formed in the IMD L8.Each of the lower electrode 240 a, the dielectric layer 245, and theupper electrode 250 a′ may be formed to a thickness of about 300 Å to1000 Å.

Two passivation layers P1 and P2 are formed on the IMD L9 where finalmetal interconnections are formed, and Al pads 302 and 304 are formed onthe resultant structure to connect the metal interconnections toexternal terminals.

As described above, in the present invention, an MIM capacitor is formedon a via-level IMD, and a lower electrode of the MIM capacitor isconnected to a lower metal interconnection by a photolithography processusing an alignment key for aligning the MIM capacitor. Thus, the MIMcapacitor can be formed without modifying a dual damascene process andusing additional photolithography processes. Consequently, an ideal MIMcapacitor can be fabricated and a copper dual damascene process can bereliably carried out.

While the present invention has been particularly shown and describedwith reference to a preferred embodiment thereof, it will be understoodby those of ordinary skill in the art that various changes in form anddetails may be made therein without departing from the spirit and scopeof the present invention as defined by the appended claims.

1. A method of fabricating a dual damascene interconnection with ametal-insulator-metal capacitor, the method comprising: forming avia-level intermetal dielectric on a substrate where first and secondlower metal interconnections are formed; forming a via hole forconnecting a lower electrode of a metal-insulator-metal capacitor andthe first lower metal interconnection by patterning the via-levelintermetal dielectric; sequentially forming a metal layer for acapacitor lower electrode, a capacitor dielectric layer, and a metallayer for a capacitor upper electrode on the entire surface of thesubstrate; forming the metal-insulator-metal capacitor, which includes alower electrode, a dielectric layer, and an upper electrode, bypatterning the metal layer for the lower electrode, the capacitordielectric layer, and the metal layer for the upper electrode, which aredisposed over the via hole; forming a trench-level intermetal dielectricon the via-level intermetal dielectric including themetal-insulator-metal capacitor; simultaneously forming a groove for adual damascene interconnection, exposing the second lower metalinterconnection, and a trench exposing the upper electrode by etchingthe via-level intermetal dielectric and the trench-level intermetaldielectric; and forming a dual damascene interconnection connected tothe second lower metal interconnection and an upper metalinterconnection connected to the upper electrode by filling the groovefor the dual damascene interconnection and the trench with a metal. 2.The method of claim 1, wherein the formation of the first lower metalinterconnection and the second metal interconnection comprises: formingan insulating layer on the substrate; and forming the first lower metalinterconnection and the second lower metal interconnection by fillingthe insulating layer with a metal using a damascene process.
 3. Themethod of claim 1, wherein the via hole is formed in a hole shape. 4.The method of claim 1, wherein the via hole is formed in a line shape.5. The method of claim 1, further comprising: forming an etch stop layerbetween the first and second lower metal interconnections and thevia-level intermetal dielectric; and forming another etch stop layerbetween the via-level intermetal dielectric and the trench-levelintermetal dielectric.
 6. The method of claim 1, further comprisingforming the metal-insulator-metal capacitor using one masking processand then reducing the area of the upper electrode by etching edges ofthe upper electrode.
 7. The method of claim 1, wherein the lowerelectrode directly contacts the first lower metal interconnection by thevia hole.
 8. The method of claim 1, after forming the via hole, furthercomprising forming a via for connecting the lower electrode and thefirst lower metal interconnection by filling the via hole with aconductive material and then planarizing the filled conductive material.9. The method of claim 1, wherein the formation of the groove for thedual damascene interconnection includes forming the via hole and theline trench using a via-first dual damascene process.
 10. The method ofclaim 9, wherein, while the line trench is being formed, the trenchexposing the upper electrode is formed.
 11. The method of claim 1,wherein the formation of the groove for the dual damasceneinterconnection includes forming a via hole and a line trench using aline trench-first dual damascene process.
 12. The method of claim 1,wherein the dual damascene interconnection is formed of at least onematerial selected from the group consisting of copper, gold, silver,tungsten, and any alloy thereof.
 13. The method of claim 1, wherein,while the via hole for connecting the lower electrode of themetal-insulator-metal capacitor and the first lower metalinterconnection is being formed, an alignment key for aligning themetal-insulator-metal capacitor is formed by patterning the via-levelintermetal dielectric.
 14. The method of claim 13, wherein the formationof the metal-insulator-metal capacitor includes leaving the metal layerfor the lower electrode, the capacitor dielectric layer, and the metallayer for the upper electrode on the inner walls of the alignment key byperforming an anisotropic etchback process.
 15. The method of claim 13,wherein, while the dual damascene interconnection and the upper metalinterconnection are being formed, a dummy interconnection is formed byfilling a stepped region of the alignment key.